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 A006758 Number of strictly 2-dimensional one-sided polyominoes with n cells. (Formerly M4114) 4
 0, 0, 0, 1, 6, 17, 59, 195, 703, 2499, 9188, 33895, 126758, 476269, 1802311, 6849776, 26152417, 100203193, 385221142, 1485200847, 5741256763, 22245940544, 86383382826, 336093325057, 1309998125639, 5114451441105, 19998172734785, 78306011677181, 307022182222505, 1205243866707467, 4736694001644861, 18635412907198669 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS A000988 is the main entry for this sequence. This version counts only polyominoes that are strictly 2-dimensional - it excludes those where all the squares are in a single line. Thus a(n) = A000988(n) - 1. - John Mason, Feb 18 2021 The value of a(11) in Table 1 (p. 366) of Lunnon (1975) is incorrect, and was corrected here by N. J. A. Sloane in 2011. - Petros Hadjicostas, Jan 11 2019 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS N. J. A. Sloane, Table of n, a(n) for n = 0..45 [a(0)=0 inserted by Georg Fischer, Jun 25 2020] W. F. Lunnon, Counting multidimensional polyominoes, Computer Journal 18 (4) (1975) 366-367. CROSSREFS A000988 (= a(n) + 1) is another version. A column of A195738. Sequence in context: A109311 A151350 A195741 * A123189 A219847 A047156 Adjacent sequences:  A006755 A006756 A006757 * A006759 A006760 A006761 KEYWORD nonn AUTHOR EXTENSIONS Edited by N. J. A. Sloane, Sep 23 2011 a(0)=0 inserted by Sean A. Irvine, Jun 24 2020 Name clarified by John Mason, Feb 18 2021 STATUS approved

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Last modified July 28 17:15 EDT 2021. Contains 346335 sequences. (Running on oeis4.)